Unloading valve



March '20, 1951 R, STEVENSON 2,545,712

UNLOADING VALVE Filed June 27, 1944 man ATTORNEYS Patented Mar. 20, 1951 UNLOADING VALVE Robert Stevenson, Barrington, R. I., assignor to Merit Engineering, Inc.,

Island a corporation of Rhode Application June 27, 1944, Serial No. 542,411

6 Claims. (Cl. 137-153) This invention relates to an unloadingr valve.`

for use in a system in which the fluid pressure may be maintained without constant action of the fluid pump.

One of the objects of this invention is to provide -a valve through which uid may pass tov supply pressure for transfer of the fluid and yet short circuit the fluid now back to the reservoir whereby the energy required by the pump will be relieved.

Another object of this invention is to provide a valve in which the fluid passing through the valve will automatically short circuit whena predetermined pressure is reached and thereby relieve the pump which operates on thevalve from the work which it has to do when this short circuiting arrangement is not cut in.

Another object of this invention is to provide a quick operating valve and consequently one in which the control of the system may be closely obtained. l

Another object of the invention is to .provide n sliding packing which is exposed to the high pressure fluid when the valve is inA unloading position and it is desired to maintain the system at high pressure without subjecting the pump to high working conditions.

Another object of the invention is to provide two rigid seats for the valve against which the high pressure works.

Another object of this invention is to provide an arrangement whereby the valve mayY be easily and quickly adjusted.

Another object of this invention is to provide a cartridge which may be removed from v the valve without disconnecting the valve from itsv communicating conduits. t

Another object of this invention is1 `to provide aV removable cartridge which may be preadjust'ed and merely insert it into the valve for a predetermined value of operation of the valve or which may be interchanged with another cartridge for a change of such predetermined adjustment.

With these and other objects in view, the invention consists of certain novel features of construction, as will be more fully described and particularly pointed out in the appended claims.

In the accompanying drawings: Fig. l is a sectional view through the valve; Fig. 2 is a sectional view through a removable unit which may be inserted in the valve body;

and

Fig. 3 is a diagrammatic view illustrating a system employing the unloading valve.

In proceeding with this invention I provide a equal pressure.

valve body which has a port to connect with a high pressure supply and a port to connect with the work with a passageway between these ports. A low pressure port is also provided in the valve with a'conduit connecting with a passageway for the high pressure uid. These passageways are controlled by a main valve with a check valve therein by an arrangement such that the high pressure will press upon opposite ends of the valve, the surfaces of said valve which are exposed to the pressure being of such relative diameters that the unbalanced pressure due to the differential of the diameters determines the direction in which the valve will be moved. A spring supplements the larger diameter and the pressure on this larger" diameter is so controlled that when pressure is permitted upon this larger diameter they valve will be closed but when the control acts to remove this pressure on this diameter will overcome the spring and cause the` valve to open. This control is by a predetermined arrangement So that automatic operation will be had, the arrangement being such that the main valve will open at a predetermined high pressure and will close'at a predetermined lower pressure. When the main valve is open fluid pressure may short circuit to the low pressure port and less work need be done by the means which supply the fluid to the high pressure port.

A system in which the valve is used is illustrated in Fig. 3 wherein a reservoir is shown from which a pump takesliquid for supplying it to a cylinder A at either, end of the cylinder by reason of the four-way valve B. An accumulator may be in the line for maintaining a somewhat As the fluid is supplied at one end of the cylinder to move the piston therein, fluid is extracted from the opposite end of the .cylinder and returned to the reservoir. My unloading valve i0 is located in this line between the pump and the work in the location illustrated in this figure and a return line C is provided from another port of the valve to the reservoir. One port 20 of the valve is connected to the pump by conduit E, a second port I8 is connected to the work by conduit D and another port 23 is connected by the returnline C to the curs the pressure rapidly builds up. When this pressure builds up to 1000 pounds my unloading valve will automatically operate so as to switch the circulation from the work to the by-pass through conduit C back to the reservoir, thus reducingthe v load on the pump considerably.

Withirefe'rence to the drawings. i0 designates a valve body formed of a block of metal which has a main bore Il for the main valve threaded as at l2 and enlarged as at i3 at one end While more restricted portions I4 and l5 "provide shoulders i5 and Il. The portion I6 of this bore provides a port I8 for a high pressure discharge which may be threaded asat l9`for'connection of some suitable conduit such as D leading to the work. The body may havela'noutwardly'projecting boss 22 in which a pressure supply'port 2B is located which is provided with'internal threads 2i for connection to some suitable conduit Eto the pump and'which communicates with the bore il. A low pressure port23 isalso provided in this boss havingjthreads 2:3 for connection to s'omesuitable conduit C returning to "theI reservoir. This vport alsoV connects 'with the 'mainbore H. v

`A smaller bore 25 is'also provided in the body f the axisof whichis parallel to the borev l l. This 'bore is of the'saine'size throughout its eX- tentl from one end of the body to the other and passage i2'! 'adjacent one` 'end Yand through a passage "28 adjacent the other end of the valve b'ody. g

In the' main'va'lve bore H, l position'a Vblock S 'of generally tubular formation which at its Yend 3l engages the yshoulder `l7l,"v .1hile a "soft 'packing '32`serves to seal'thise'nd'of the block 'in the bore Il. tending laterally of the block communicate with the annular chamber 31% 'formed 'by' thereduced :pcrtionof the block between itself andthe borev I l at a 'lo'cationfso that"this'annular chamber communicates Vwith the `high pressure" port 2S. `A`suitable softpacking 345 serves to seal the "block" with the bore H Vorrthe opposite side-0f v'this annular chamber' 34. A Vvalve seat is provided "at one 'end Aof thisblockat the yjunc- 'tion of the inner surface of the b cre and against which the main valve is seated. VThe inner sur- 'jface Vat `the 'opposite end of this block'designated 3l provides a sliding guide forone end'of Ythe 'A plurality oi openings e3 eX- valve.

A sleeve 38 has threaded engagement withthe vthreads I2of bore'llY and its'end engages the block 353 so Yas to maintain this block iirmly againstthe shoulder l1 rigidly ein place -in the Valve body. The sleeve hasv an internal bore 39 of a size Vsubstantially 'larger in diameter than the diameter of the valve seat 3S and in this bore isrlocated the main'valveV 4B.

The main valve-dll has'a ltapered surface 4i to engage the valve seat 345Y and aiiange l2y to slidingly engage thebore 39 ofthe sleeve 38.' A soft packing 43 is provided vto preventV theescape of fluid between these engaging surfaces. The valve is also providedkwith an end portion 4d Vslidingly engaging the surface 3l ofthe block-d` land connected to the reduced end of the valve -by a stud 45 eXtendingaXially through the valve' and secured by nut' and check nut 46 and The Yvalve ception of a coil spring 49 which acts to force 4 the valve toward its seat by engagement with the abutment surface 49 of the plug 58.

This plug 56 is threaded as at 5I into the end of the sleeve 38. The hollow interior of the reduced portion of this plug connects with the annular chamber between the head of the plug Vand theend of the sleeyebyreason of la plurality of openings '53 extending'through the stem of the plug. This annular chamber 52 is in com- "munication with the conduit 28 so that liquid wmaybe supplied through this passage 28 to the chamber 5ft on the enlarged end of the valve. A suitable' soft packing seal 55 is provided in the sleeve' at one side of the annular chamber 52 and a soft packing 56 is provided in the plug on the other sidef the annularY chamber 52 to prevent the escape of the high pressure iluid 'along Athese surfaces.

The unit 2t which is inserted in the bore comprisesja sleeve ed of a size to slide vv-within the bore 25. The sleeve is lreduced lin diameter-at certain pointsfal'cng its extent as atv lso as 4to provide an annular chamber fibetweent'vand thebo're v25. Openings 63 from this chamber 52 '755,n throughy openings '16','which annular Achamber 'l5-is in connection with the-ccnduit V8 and the chamber 52.

The upper end ofthe boreprovides a valve 'seat 16' against which lthe inclined 'surface 'I1 of a valve 78 mayenga'ge to close this'bore 65.

The flared-end itl of theV valve 'engages Athe bore 611 and is Vguidedl alongu this surface. `Openings 80 through this flaredlportcn of 'the valve serve for free communication of the' high pressure huid tothe innerconi'cal surface of this ared portion and serve to balance all'prtions of this end-'ofthe valve except vthe diameter which engages the valve Y"seat, `fI`he valve-"immediately below the valve seat'isy of vreduced diameter but atapoint belowconduit Il the valve has alporand is closed by'aball 85 which vis pressed by the plunger 73 to seating position-through means ofa coil -spri-ng'u'fhaving Vone end engaging the abutment? threaded Yasat for movement longitudinally of the bore S9.

lThe sleeve y:Eil is internally threaded at its oppposite'ejndsVT as at 9i) and 9| into which plugs '92 and 93 may threadingly'engage.

The heads of these plugsl are sealed by soft packings 94 and 35 which are located beneath theheads of these plugs and the endsof vthei sleeves 6B. YThese Y sures tending to oppose will pass from the port 20 past the 50 so to prevent" relative turning of these parts with reference to each other and to the body.

The guided end portion of the main valve is provided with a check valve |00 which is forced to its seat by a spring |0| abutting the perforated plate |02 secured in the end of the main valve. Pressure is communicated from the inlet high pressure port |8, also by reason of the conduits 2l, 65, 1|, l0, 12, ld, 15, 15, 28, 52, 53 and 54,'high pressure is transferred from one end of the main Valve 40 on one side of the valve Y seat 36 to the other end of the valve at the lother side of the valve seat 36. The diameter of the valve head 42 at one end of the valve determines the closing pressure which will be applied on the valve which is assisted by the spring 49. Pressure exerted tending to open this valve presses on an area of the valve equal tothe diameter of the seat 35. The remainder of this end of the valve is all in balanced relation. A complete balance may be provided using pressure of spring 49 alone for closing.

It is so arranged that if the pressure on the area 42 of the valve is cut off, then the pressure on the opposite end of the valve will overcome the pressure of the springe49 and open the valve. The check valve |00 prevents pressure from the line D escaping to the return C. The automatic cut-off of the pressure on the area 42fis provided by the pilot valve in the bore 25 and which is a separate unit as shown in Fig. 2.

The ball 85 normally closes the opening 84 and at the same time the spring which forces this ball to its seat also forces the valve 18 from its seat 15 so that it is normally open.

When the ball 85 is seated, the surface area thereof exposed to high pressure as to provide an unbalanced force acting on the ball in a direction tending to move the same towards its seat. The surface area of the ball exposed to this force is an area equal to the area of the opening 84.` The spring 86 supplements this force. The surface area of the valve 18 subjected to pressures tending to slidably move the same toward or from its seat is balanced such that the effective area thereon exposed to pressure tending to move the same to its seat, when the ball 85 is seated, is an area equal to the area of the bore 65 minus the area of the opening 84.

The adjustment of the spring 3G is such that itwill yield when the pressure reaches top limit of the range. This may be assumed to be 1,000 pounds. Such pressure on the valve 18 will move the same to its seat against opposing pressure on the ball 85 and resistance of spring 86. With the ball valve 85 removed from its seat, fluid will escape through opening 84 and will reduce the pressure opposing the valve 18. With the valve 'I8 seated, the surface area exposed to presmoving the same from its seat is equal to the total area of the bore 55 and will maintain the valve closed against the action of spring 86.

When the ball 85 is forced from its closed position liquid may escape through the opening 84 to the recess 66, thence through the opening 6l through the annular chamber 68, and thence to the port 23 and low pressure side of the valve. The closure of the valve at 16 prevents high pressure fluid from being supplied to chamber 54 and area 42 of the head of the valve. Thus, by the absence of this pressure the main valve will open andthe incoming fluid from conduit liquid is such valve .seat

6 v3|; to the port 23 andfthrough conduit C back to the reservoir and this condition will occur until the pressure in the work line drops to an extent, say 800 pounds, when. the spring 8B will overcome this pressure, open the valve ll, close Valve 85, and open the pilot valve and permit liquid to be supplied to the chamber 54 under the higher pressure and consequently press upon this larger diameter of the valve at this end to l close the same. Thus the opening pressure and the closing pressure are inversely proportional to the opening area and closing area.

A relief valve' |05 may be placed in the line E with a return connection F to the reservoir.

I claim:

l. In an unloading valve having a body provided with a supply port, a discharge port and a return port communicating with the supply portV a main valve normally seated to close communication between said supply port and return port and subjected on one side thereof to the pressure at the supply port tending to unseat said' valve and on the other side to the pressure at the discharge port tending to seat said valve, a check valve between the supply and discharge ports for blocking the returnof iiuid from said discharge port so proportioned with reference to the main valve as to area and spring pressure as to be unseated when said main valve is seated and seated when said main valve is unseated, a ncrmally unseated second valve for controlling the said fluid pressure from said discharge port which acts on said main valve, said second valve being subjected on one side to the pressure at the discharge port tending to seat said second valve to cut off said pressure from said discharge port which acts on said main valve, a vent conduit in said body communicating with said return port for draining upon the seating of said second valve the said pressure from said discharge port which acts on said main valve for creating a diierential pressure condition r`across said main Valve to unseat the same in response to the said pressure from the supply port which acts thereon, a third valve for controlling said vent conduit arranged to be normally seated and subjected on one side to the pressure at the discharge port tending to move the same to closed position and engaged on the other side by said second valve to be unseated thereby upon seating of said second valve and a spring supplementing the said fluid pressure acting on said third valve to oppose closing of said second valve and adjust-- able means to predetermine the uid pressure range at which said second valvewill foe or unseated.

2. In an unloading valve, a supply port, a discharge port, a passage for fluid between said ports, a return port communicating with the supply port, a conduit therefrom to said passage providing a valve seat, a main valve arranged to be normally seated on said seat and subjected on one side thereof to the pressure at the supply port tending to unseat said main valve and on L.the other side to the pressure at the discharge port tending to seat said valve, a check valve between the supply and discharge ports for blocking the return of fluid from said discharge port so proportioned with reference to.the main valve as to arealand spring pressure as to be normally unseated when said main valve is seated and seated when said main valve is unseated, a second conduit for supplying fluid from the discharge port to said'main valve. a second valve in said 54ans second conduit normally unseated and subjected on one side thereofv to the huid pressure in said second conduit tending to seat the same to closel said second conduit to cut off the fluid from said Y pressure condition across said' main valve to unseatv the same in response to the said pressure from the supply port which acts thereon, a third valve for controlling said' vent conduit arranged to be normally seated to close saidA vent conduit and subjected on one side thereof to the fluid pressure in said second conduit tending to seat said third valve and engaged on the other side by saidl second valve to be unseated thereby upon seating of said second valve, and a spring supplementing the said fluid pressure which acts on said third valve to oppose the seating of said second Valve and adjustable to predetermine the uid pressure range at which saidv second valve will be seated and saidV third valve opened.

3. In an unloading valve, a supply port, a discharge port, a passage for uid between said ports, a return port communicating with the supply port, a conduit therefrom to said passage providing a valve seat, a' main valve arranged to be normally seated on said seat and subjected on the high pressure side of said seat to the pressure at the supply port tending to unseat said valve andA on the low pressure side of vsaid seat to the pressure at the discharge port tending to seat said main valve, a check valve in said rnain valve located between the supply and discharge ports for blocking the return of fluid from said discharge port so proportioned with reference to the main valve as to area and spring pressure as to be seated when said main valve is unseated and unseated when said main valve is seated, a spring on the low pressure side of said seat urging said main valve lto seated positior1,ra second conduit from said passage to supply fluid from the said discharge port to said rnain valve, a second valve in said` second conduit normally unseated and subjected on one side thereof to the iluid pressure in said second conduit tending to seat said second valve to close said second conduit to cut on" the fluid from said discharge port to said main valve, a vent conduit from said second conduit to said return port to drain' fluid from said second conduit upon seating of said second valve to create a differential pressure across said main valve to unseat thev same in response to the said pressure from the` supply port which acts thereon, a third valve for corrtrolling said vent conduit arranged to be normally seated and engaged on one side thereof by said second valve and unseated thereby upon the seating of said second valve, said third val'v'e being subjected on the other side thereof. toA the fluid pressure in said second conduit tending t'o seat the same and oppose seating of saidse'c'ond valve, spring pressure urging said third valve' to seatedposition and adjustable to predeterin'ine the pressure range at which said second" valve will beseatedl and said third Valve unsfeated;

4. In anv unloading. valve, a` supply port', a dis.. charge port, a passage for fluid between said ports, a return port communicating with` the supply port, a conduit therefrom toA sa'i'd passage providing a valve seat, a main valve engaging saidseatand'.arrangedto be normally seated and subjected on the high pressure side of said'se'a't to the pressure at' thesup'ply port and on' the 8 iow pressure 'side' of said seat to the pressure at the discharge port', said valve having a' portion thereof sldabljj" extending into said passage and provided with a bore therein comrnunic'atingl with said supply port and said discharge' port, a 'check valve in said bore between the' supply Yandv'dis'- charge ports for blocking theY return of fluid from said discharge port so' proportioned with refer; ence to' the rnain valve as to area and spring pressure as' to be seated' when said main valve is uns'e'ated and unseated when saidmairrvalv is seated, a spring on the low pressure side of said' 'seat urging said main valve' tof seated posi'- t'ir, a second conduit from' said passage to supply fluid from' said discharge port to said r'nain valve, a second valve' in said second condui't arranged to be' normally unseated and subjected' o`n one side thereof to the' 'uid prssu'rei'n said secon'd conduit tending to seat the same to c'los'e" said' second conduit to cut off the' fluid from said discharge port to' said main valve', a Vent conduit from said secondconduit to" said return port to' drain fluid from said second conduit upon seating ofl said second valve to create a differential pressure across said main valve to unseat the saine in response to the said pressure at the supply port which acts thereon', a' third valve for controlling said vent conduit arranged to be" normally seated and engaged on one side thereof by'said second valve and unseat/'ed thereby upon the seating of said' second valve and subjected on the other side thereof to fluidI pressure in said second conduit tending to seat said third valve to oppose seating of said: second valve, spring pressure urging said third valve to seated position' and adjustable to predetermine the pressure range at which said second valve will be seated and: said third valve unseated.

5. In an` unloading' valve, a' supply port, a dis'- charg'e' port, a passage for' nuid between said ports', a return port communicating withA the si'ipplyv port, a conduit therefrom to said passage providing a` valve seat', a main valve engaging said seatVV and arranged to be normally seated and subjected' on the high pressure side' of said s e'atf to' the pressure at the supply port andV on the low pressure side of said seat to the pressure at the discharge port, said'valv'e having a'portion thereof'slidably extending'into said passage and provided with a bore therein communicating with said supply port andsaid discharge prt; acheck valve'v in said b'ore between the supply andldis'- ch'arg'e p'orts for blocking the ret-urn ofuidfrom said discharge port soY proportioned' with' reference' to the main valve as to area and spring pressure as to be seated when said main valve is unseat-ed and unseated when said main' valve is seated, said portion having' anl abutment thereon and a spring acting between's'aidabut'- rnent and said check valve urging said check valve to seated position; a spring on the low pressure side of said seatl urging said mainvalve to seated position, a second conduit from said passage to supply iluid from saidA discharge' port to'saidm'ain valve', asecond valve insaid second conduit arranged to be normally unseated and subjected on one side thereof to the fluid pressure in said' secc-nd conduit` tending toseatV the same tr,1cl'o"sesai'dl second' conduit to cutV off the fluid from' said discharge portl to lsaid niainvalve, a vent conduit from said secondi conduit to said return port to drain Huid fromsaid-secondi conduit upon' seating o'f said secor'rd valve to create a differential pressurel across said-` Inaiivalveit'o unseat the Sarnel in response to thev sid" pressure at the supply port which acts thereon, a third valve for controlling said vent conduit arranged to be normally seated and engaged on one side thereof by said second valve and unseated thereby upon the seating of said second valve and subjected on the other side to fluid pressure in said second conduit tending to seat said third valve to oppose seating of said second valve, spring pressure urging said third valve to seated position and adjustable to predetermine the pressure range at which said second valve will be seated and said third valve unseated.

6. In an unloading valve having a body provided With a supply port, a discharge port and a return port communicating with the supply port, a main valve normally seated to close communication Ibetween said supply port and return port and subjected on one side thereof to the pressure at the supply port tending to unseat said Vvalve and on the other side thereof to the pressure at the discharge port tending to seat said valve, a check valve between the supply and discharge ports for blocking the return of uid from said discharge port so proportioned with reference to the main valve as to area and spring pressure as to be unseated when said main valve is seated and seated when said main valve is unseated, a conduit in said body for supplying uid from said discharge port to said main valve, a, vent conduit from said conduit to said low pressure port, a valve unit in said conduit including a sleeve provided with passages therein communicating with said discharge port, main valve and said vent conduit, a second valve in said unit arranged to be normally unseated and 3 subjected on one side thereof to the fluid pressure in said conduit tending to seat said second valve to close said passages to cut off fluid from Number Name l Date 25 2,188,463 Mercier Jan. 30, 1940 2,241,665 Herman May 13, 1941 2,264,375 Hill Dec. 2, 1941 2,279,571 Kane Apr. 14, 1942 A 2,312,877 Campbell Mar. 2, 1943 30 2,327,942 Thoresen Aug. 24, 1943 2,404,102 Schultz July 16, 1946 2,410,751 Schultz Nov. 5, 1946 2,447,820 Schultz Aug. 24, 1948 5 FOREIGN PATENTS Number Country Date 8,799 Great Britain May 3, 1895 Great Britain June 23, 1927 i0 said discharge port to said main Valve, a ball valve in said unit arranged to =be normally seated to control the said vent conduit and subjected on one side thereof to the fluid pressure in said conduit tending to seat the same and engaged on the other side thereof by said second valve to be unseated thereby upon the seating of said second valve to drain uid in said conduit from said'main valve to create a differential pressure across the main valve to unseat the same in response to the said` pressure at the supply port which acts thereon, and a spring urging said ball valve to seated position and oppose seating of said Second valve and adjustable to predetermine the pressure range at which said second valve will be seated or unseated.

ROBERT STEVENSON.

REFERENCES CITED The following referenties are of record in the file of this patent:

UNITED STATES PATENTS 

